The use of combustion for the disposal of wastes has long been a known technique. By combustion of the waste material, the bulk is greatly reduced and heat recovered from the combustion can be used as an energy source.
Numerous types of combustors for waste material have been proposed. A useful type of combustion unit is that type described in U.S. Pat. Nos. 3,822,651; 4,066,024 and 4,226,584, the contents of those three patents being incorporated by reference herein, generally known as the O'Conner combustor. This type of combustor uses a rotary kiln that is formed by a plurality of pipes that form an inner cylindrical surface, the pipes adapted for flow of water therethrough, with steam produced that is separated from the water in the pipes. Air is charged to the kiln through porous means intermediate the pipes of the combustion unit, and combustion gases from the unit pass to a boiler for further production of steam. This type of combustor has been found very useful in waste disposal while providing revenue through generation of steam and electric power. An installation using such a combustor is the Resource Authority in Sumner County waste-to-energy plant at Gallatin, Tenn., which processes trash from the surrounding area and routinely reduces the volume of the trash by more than ninety percent, with resultant ash hauled to a landfill.
While such a waste disposal system is useful in processing of common waste materials, such a system may not be suitable for use in disposal of waste material which may contain hazardous waste constituents such as polychlorinated biphenyls (PCB's), or the like. Since such hazardous waste constituents, whether initially present in the waste or added thereto for disposal purposes, are relatively high boiling organic compounds, a small amount may escape combustion and destruction in the combustion unit and may pass through the system in the neighborhood of relatively cool walls. Although the proposed mechanism of escape from the system is likely to account for only a small fraction of the feed, environmentally imposed limits may preclude even such small residues. Even if afterburners or some other means to completely combust the residual hazardous waste material were to be used, considerable incremental capital and operating costs would be associated with such a system.
The proper disposal of hazardous chemical waste has become a major focus of governmental agencies. In the incineration of PCB's, for example, stringent requirements must be met as imposed by the Environmental Protection Agency. It is thus imperative that efficient and effective means for waste treatment be used so that hazardous materials can be safely disposed of, and soils contaminated with hazardous materials can be reclaimed.
It is an object of the present invention to provide a waste disposal system that will dispose of waste by combustion and remove residual solid and vaporous waste constituents from the combustion gases discharged from a combustion unit.
It is another object of the present invention to produce, from waste combustion gases, a substantially uniformly high temperature, clean, waste-free gas from which heat values can be recovered.
It is another object of the present invention to provide a system for disposal of waste materials and destroying hazarous wastes from contaminated soils while providing steam as an energy source.